The brain is exceptionally sensitive to the effects of lead poisoning and it is the young, from birth to about 7 years of age, who show the most serious brain damage following lead poisoning. Poisoned individuals who survive often have permanent brain damage which can lead to periodic convulsions, irritability, hyperactivity, retardation of normal mental development, emotional instability, behavior disorders, low attention span, impaired motor development, and anti-social behavior. Effects of relatively low level, chronic lead exposure on brain function of the young during their earliest period of life when the brain is undergoing rapid growth and development into specialized function has not been systematically studied. After lead is given to newborn rats, they develop many of the symptoms seen in children poisoned by lead. Under certain conditions of mild lead poisoning the developing young rat does not develop gross brain damage but does have abnormal behavior such as hyperactivity, aggressiveness and strange repetitive habits and body motions. Experimentally, the goal is to relate three conditions: (1) lead exposure to (2) abnormal behavior to (3) discrete neurochemical changes resulting from lead exposure. Newborn rats and coetaneous controls will be fed lead (or non-lead solutions) to simulate pica. Body activity will be monitored through 24 hour cycles. At suitable ages brain tissue will be examined for neurotransmitter and monoamine content. Certain centrally active drugs will be used to reverse behavioral changes caused by lead.